go 36's+ I run 37's on profields (not really any stronger that stock) and I haven't had a problem. I'm running the same duals 2.28x2 with 5.29 and f/r lockers. Love my tires wouldn't ever go smaller now. I'm not sure what in the drivetrain will have a problem with those tires except for the birfs and you already said you have longs, so go for it